QTL Mapping And Candidate Gene Analysis Of Plant Height In Flax (Linum Usitatissimum L.)

Flax(Linum usitatissimum L.)is one of the main oil crops in China.It is mainly distributed in northwest and north China with strong drought tolerance and cold tolerance.Its oil is rich in ?-linolenic acid,which has health benefits such as lowering blood lipid,preventing cardiovascular disease,anti-inflammation and improving memory.With the improvement of people's quality of life,flax oil has been paid more and more attention with better development prospect.Plant height is one of the important agronomic traits of crops,which not only affects the yield of flax,but also has a certain effect on the quality of flax seed.Recombinant inbred line(RIL)population derived from Heiya No.14 and Macbeth is employed for plant height QTL mapping.We identified one candidate gene by combining QTL-seq and traditional QTL mapping method.The expression vector containing plant height candidate gene was constructed,and the phenotype observation and high trait statistics were carried out.The main results are as follows:1.The extreme phenotype(high and low plant height)gene pool was constructed thtough plant height statistics and analysis of the RIL population of No.14×Macbeth.10 plant height candidate genes were identified by QTL-seq based on next-generation sequencing of flax genome and the SNP index analysis.In combination with the traditional QTL positioning method,Lu CWINV1-1 was further identified as a candidate gene of flax plant height.2.Acid invertase gene family in flax was predicted in flax genome database,which contains 11 cell wall invertase genes and 7 vacuolar invertase genes.Evolutionary analysis showed that the acid invertase was divided into two subgroups: the cell wall invertase group and the vacuolar invertase group,which is similar with other crops.3.Endogenous gene expression analysis in Macbeth and Heiya No.14 showed that the amount of gene expression in stems and leaves had no obvious difference in the fast growing period,and the gene expression in Macbeth leaves increased at 7-9 weeks during the maturation period.4.The sequencing analysis showed that there was a difference in the genome sequence of Lu CWINV1-1 gene between Heiya No.14 and Macbeth.Arabidopsis of Lu CWINV1-1Mac transgenic lines grows slowly and become crimp on early stage,and gradually become normal,which leads to longer life cycle while Lu CWINV1-1Hei transgenic lines have no significant difference to wild type.The result showed that plant height of Lu CWINV1-1Mac and Lu CWINV1-1Hei transgenic lines both changed compared to wild type.